Relative position detecting apparatus between gas working tool and workpiece



Nov. 17, 1970 ROKU suzu ETAL 3,540,263

RELATIVE POSITION DETECTING APPARATUS BETWEEN GAS WORKING TOOL AND WORKPIECE Filed March 27, 1969 P 12 is //5 P 6 20 I fi 29- i9 4 mvzwrons 9 aoxu suzuxx HAJIME KASAHARA HIDETAKA SHIGEIZUMI EIZI AIZAWA C4562; r-JQ ATTORNEYS United States Patent O 3,540,263 RELATIVE POSITION DETECTING APPARATUS BlliggyiEEN GAS WORKING TOOL AND WORK- P Roku Suzuki, Tokyo, Eizi Aizawa, Funabashishi, Hidetaka Shigeizumi, Tokyo, and Hajime Kasahara, Omiyashi, Japan, assignors to Koike Sanso Kogyo Co. Ltd., Tokyo, Japan, a corporation of Japan Filed Mar. 27, 1969, Ser. No. 810,969 Int. Cl. G01b 13/12 US. Cl. 73-375 Claims ABSTRACT OF THE DISCLOSURE This invention comprises two elements of a back pressure detecting device and a transmuting device, the former having a chamber provided with a jet from which a pressurized fluid is ejected toward a workpiece to generate a back pressure and plural inlets arranged so as for the fluid to be ejected thereinto from different directions for generating a turbulence therein and at detecting port for detecting the back pressure, while the latter transmutes the back pressure detected by the detecting device into electric signals to activate suitable control mechanisms.

BACKGROUND OF THE INVENTION In gas working such as gas cutting, the relative distance between a nozzle, or a tool for cutting, and a workpiece surface to be cut must be always in a predetermined value during cutting working for performance of a good cutting. Taking into account such matter, an automatic control of the distance in a constant value has heretofore been carried out by means of causing a proper fluid to eject from a jet, which is integral with a nozzle, in a usual manner to generate a back pressure and detecting constantly changes of the back pressure arising due to the variation of the distance. Back pressures obtained in this manner, however, are ordinarily so low that the nozzle (or jet) must be positioned very close to the surface of the workpiece in order that small changes in the back pressure could be detected. As a consequence, protrusions or deformations in the workpiece surface often obstructed the path of travel of the nozzle thereacross which severely limited the effectiveness of this method.

SUMMARY OF THE INVENTION This invention relates to an apparatus detecting the distance between a tool, or a nozzle, and a workpiece in gas working and more particularly to an apparatus comprising a back pressure generating device and a pressure transmuting device, the former being provided with a chamber having a jet from which a pressurized fluid is ejected toward the workpiece surface to generate a back pressure and plural inlets of the pressurized fluid located so as for the fluid to eject thereinto from different directions and a detecting port at which the back pressure is detected, while the latter is adapted to transmute the detected back pressure into electric signals.

In the back pressure generating device, the fluid ejecting into the chamber through the inlets comes to generate a large turbulence therein due to its ejection from differ- 3,540,263 Patented Nov. 17, 1970 ice DESCRIPTION OF THE DRAWING FIG. 1 schematically depicts one form of the invention; FIG. 2 is an enlarged sectional elevation of a back pressure detecting device of that shown in FIG. 1; FIG. 3 is an enlarged diagrammatic view of a pressure transmuter used in the form of FIG. 1; FIG. 4 is a circuit diagram employed in the pressure transmuter in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing, 1 is a body member having a bore (not shown) into which the top portion of a nozzle (not shown) is to be fixedly fitted. 2 is a chamber formed in body member 1 and having inlets 3, 4 of a pressurized fluid with respectively conduits 5, 6 in the back thereof and a jet 7 for ejecting the fluid onto the workpiece 8, the inlets being arranged so as for the fluid to eject into the chamber from different directions for generation of a turbulence of the fluid in the same, 9 is a. line having a detecting port 10 at one end thereof which is located within jet 7, while other end thereof is connected with a transmuter 11. The principle of the transmuter'is shown in FIGS. 3 and 4. That is, a diaphragm 12 is subjected to back pressure P to impart the same to a strain gauge 13 through an inserter 14, while another diaphragm 15 transmits likewise an air pressure P (atmospheric pressure was employed in this embodiment) to a strain gauge 16 through an inserter 17. The change of pressure P converted into a change of resistance in the strain gauge 13 will be taken out at output sides 18, 19 in a bridge circuit shown in FIG. 4 wherein 20, 21 are constant input electrical sources. Such transmuter may be substituted by any other suitable known device. In FIG. 1, 22, 23 show schematically an amplifier and control mechanism respectively.

In a test of the invention, a back pressure of 300 (mm. mercury) was obtained where a compressed air of 5 kg./cm. was ejected into the chamber from the two inlets, taking a distance of 5 mm. between the jet (or the nozzle) and a workpiece.

The detecting apparatus of the invention may be eflectively applicable to gas cutting, gas scarfing work and otherwise workings for detecting an apposite distance between a tool and a workpiece under insurance of a safety operation.

We claim:

1. A relative distance detecting apparatus comprising a body member having a chamber formed therein with a jet for ejecting pressurized fluid toward a workpiece to generate a back pressure, a detecting part for detecting the back pressure, and plural inlets in said body member for delivering 1fluid thereinto from diiferent directions to References Cited create a turbu ence therein.

2. The apparatus of claim 1 including a transmuting UNITED STATES PATENTS device for transmuting a back pressure into electric sig- 2,266,566 12/1941 Poole 73-375 nals, and a conduit communicating said detecting port 2900468 8/1959 with Said transmuter. 5 2,982,124 1961 KllObel 7337.7 3. The apparatus of claim 1 wherein said body mem- 3194O55 7/1965 Knobel her is integral with that which is to be attached to the FOREIGN PATENTS top portion of a nozzle fixedly. 65

4. The apparatus of claim 1 wherein said detecting 10 00341 7/1966 Netherlandsport is arranged Within said jet.

5. The apparatus of claim 1 wherein said pressurized LOUIS PRINCE Pnmary Exammer fluid is a compressed air. W. A. HENRY II, Assistant Examiner 

